typo in antiwindup #59

Author: askuric

src/common/pid.cpp

@@ -29,7 +29,7 @@ float PIDController::operator() (float error){
     // Tustin transform of the integral part
     // u_ik = u_ik_1  + I*Ts/2*(ek + ek_1)
     // method uses the antiwindup Foxboro method : https://core.ac.uk/download/pdf/289952713.pdf
-    float integral = integral_prev + I*Ts*0.5f*(error + error_prev) + integral_antiwindup_prev*I;
+    float integral = integral_prev + I*Ts*0.5f*(error + error_prev) - integral_antiwindup_prev*I;
     // antiwindup - limit the output
     float integral_constrained = _constrain(integral, -limit, limit);
     integral_antiwindup_prev = integral - integral_constrained;